Sheet glass



v 1,645,054 Cd. 11, 192|. G. E. HOWARD METHOD OF AND APPARTUS FORFORMING SHEET GLASS Filed oct. 13, 192e :s sheets-Sheet 1 INVENTOR l645.054 Oct. ll, 1927. G. E. HOWARD METHOD OF AND APPARATUS FOR FORMINGSHEET GLASS Filed Oct. 13, 1926 3 Sheets-Sheet 3 jig. 7 so ll t" f/ l YlN'vEN-ron Patented Oct. 11, 1927.

UNiTED STATES PATENT OFFICE.

":EORGE E. HOWARD. F BUTLEmlPENNSYL-VANIA, ASSIGNOR TO HARTFORD-EMPIRECOMPANY, OF HARTFORD, CONNECTICUT` A CORPORATION 0F DELAWARE.

METHOD OF AND APPARATUS FOR FORMING SHEET GLASS.

Application tiled October 13, 1926. Serial N'o. 141,278.

My invention-relates to a method and apparatus for drawingr glass, andmore particu larly to the formation ot-sheet glass known as windowglass.

My invention has for one of its objects the provision of means forreducingr defects on the surface of the :dass and particularly forlocalizinpr eertainwof those defects to asmaller area than is possible.under the present.

l0 systems.

Another object of my invention is to avoid the necessity for extremesensitiveness of control, by providing a method and appara'tus whichwill enable sheets to be drawn '5 with uniform thickness and more nearlyin' dependent of the distribution of the coolingr effect. especially onthe upper portion of the sheet before it is set.

Another object ot my invention is lo improve the character of thesui-fare of tln` glasssheetz linally drawn.

Still another object is to provide for increase in the rate. of drawwithout. holdin;r large quantities of glass at a low temperature. andthus overcome the tendency of the, glass to devitrify. I

Still another olijeet lis to maintain the straightness or planeness ofthe. sheet drawn and to do so without such sensitive attention to thecooling conditions as is necessary in the prevailingr methods.

Some of the forms of apparatnsby which my invention may be practiced areshown in the, aeeompairvine'r drawing, wherein Figure 1 .is alongitudinal seetionalvicw of a fore,- heartih or other glasscontainer,4 to which one form of my improved forni of apparatus has beenapplied, the section-lbeingr taken on the line lof Fig. 2; Fig. it is aview taken on the line II-II of Fig. 1'. Vwith a portion `of theapparatus removed; Fig. '3 isa view similar to Fig'. 1, but showing amodified torni of drawingr ring; Fig. 4 shows still another formofvdrawing ring; Fig. 5 is a plan iew of the apparatus of either Fig. 3or Fig. 4; Fig. -6 is a perspective view of a portion of thedra\vin';rring ot"` Fig. 4; Figi. 7 is a view showing a third forni of drawinyjring! which l may employ, and Fig. 8 shows still another modification ofdrawing appar-.ilus-whieh may be employed.

Referring`r now to Figs. l and 2, 1() represents a drawing rin,"x` orbasin Which has upstantling ears or lugs 1l and which is immersed in theglass contained in the tank or forehearth 12. This drawing ring orbasinv may be floated in the glass by consti-notingr it so thatv itsbuoyancy exceeds that of the glass displaced (notillustrated) or, asshown in the illustration, it may be of greater weight than the amountof glass displace'd, and supported as shown, by means of bars 1? thatextend through openings in the ears 11 of the ring and over the tankwalls. and are regulated as to height by set screws 14. In ease the ringis'designed to function as a fioater, the depth of immersion thereof inthe. glass, would be governed by weights placed upon it; regulationbeing;r effected by p'uttingr on and taking off weight, as required.

Regulation of the amount of glass flowing?r into the floater l0 isnecessary, in order to maintain an even thickness of sheet, and. itl is:important. that the glass flow'be maintained at ay uniform rate. vIt istherefore necessary that the distance between the edge of the floaterover which the glass flows Vand the top surface of,V the glass be 'afixed dist'ance. This can be done by adjusting the serews 14 manually,or an automatic means may be provided by which the raising and loweringrof this edge may conform to the variation in the level of the Surface ofthe glass in lthe tank. I

The ring*r is shown as immersed for a certain distance below the surfaceof the glass in the tank. lVhen so placed there willl be a flow of glassfrom said surface of the glass downward and over the. interior surf'fare of the (louter toward a wedge-like por# tion or rib 17, which isshown as having'an opening;r into which can be introduced eitlierheatingr or cooling elements, as may be desired. When suflieient glasshas been collected in the interior of the. ring, aglass sheet can bestarted upwardly in any Well known manner, by first inserting:r a baitand drawim,Y it uliwardly. .followedby the. sheet of glass 1G.'Thereafter the operation can be continuous.

Rollers` 15. preferably covered with asbestos or other heatvresistingmaterial, bear against the oppositel sides of the sheet 16.' Bymechanically driving these rollers an upward drawing or tractioniscplaeed upon the sheet, and it continues to rise as in well knownsheet drawing,r methods. When it has in iuence of currents of coolerai-r fromthe outside and tends to keep the glass in a homogeneous state.The interior of this cover will be incandescent at the temperaturesordinarily used in drawing glass. .Directly above the slot are coolingdevices .18 which may consist of hollow metallic members through whichwater or 'other cooling medium may be passed. These increase the rate ofcooling and reduce the amount of stretching of the sheet 16 which wouldtake place if these cooling members were omitted and they permit therolls 15 to be placedsomewhat closer to the bath. They also serve tokeep away currents of air from the surrounding atmosphere which maystrike the plate unevenly'and result in irregular thickness.

There is an unbroken connection between the surface of the glass in thering 10 and the surface of the lass in the container 12. This surface isthe cest surface known, i. e., a fairly stationary pool of glass exposedto even temperatures and having a body sullicient to retain thestability necessary in work of this kind. The surface of this glass inthe tank passes into the ring and thence outwardl in the sheet, withouttouching any object, thus insuring superior quality in said surface.

Iuasmuch as of the ring 10 are obviously at the same temperature, thereis little difference in temperasture between the surface of this glassand the interior, and the cover 12'* insures that this condition ismaintained fairly well up to the point at which the 'upward movement ofthe sheet 16 begins.

In bodies of molten glass, certain irregularities occur in practice, andthere are zones where the glass is of a di'erent nature from thesurrounding glass, owing to irregularity 'in the materials or in thefeeding thereof into the melting end of the furnace. There areoccasionally bubbles which are not relined out and which flow through tothe drawin point. In the, ordinary drawing pf win ow glass certaindili'iculties appear, especiall when these patches of different naturedg ass or lbubbles touch and attach themselves to refractory materials.vQuite frequently the patches or bubbles will adhere on one side to therefractory material or the glass and the lower part other obstruction intheir path, while the .other side will float along and be drawn up asthe glass flows downwardly in entering` the ring 10, the flow thustending to push along these particles; whereas, if the glass is drawnupwardly and subjected only to the tensionalforce, the effect of suchtension rapidl diminishes in directions away from the axial line of theplate.

In the present embodiment, these particles will be flowed or pushed bythe gravity action of the lass to the lowermost points, or pools on eacside of the wedge 17 and will thus be drawn up into the sheet 16 as awhole' instead of being stretched Aout indefinitely. Bubbles or atchesof defective Vflaca present on the sur ace of the lass -be drawn up intothe sheet, but eywill be localized and will reduce defects over muchsmaller areas. T e exception to this would bein the caso of thoseparticles or bubbles whichwould strike the outer e of the glass and theinide edge of the cater, andthere might be lod'gment of these particlesto some degree at this point, in which case such defects, if stretchedas in the present practice, would be at the edges of the sheet and notat points in the interior.. These edges are cut oil' as waste in anycam', so that their resence will not clase a loss in the marketa le portions oft y plate..l Even in this latter case the tendency to lodge'will be less in the case of the exhldjxent shown in Fig. 1, owing to thecom inedi effect of flowing and drawing, under,r which combined forces,the sheet is p'ir'oduced in my invention.

e wedge 17 is preferably supplied in its interior with a cooling a entwhose eiect will be to cool the wedge ocally and thus cool the interiorof the plate' rather than its surface. In consequence, the axis of thedrawn plate will tend to remain straight or conform tothe ridge ofthewedge for two reasons. A

1. That as the glass gets colder the drawing tension increases and itwill tend to work toward the colder point:

2. Any tendencyito shift to the right or the left will result in anincrease of tension on the opposite side of the-plate and will lessenthe effect of the owing force, and the combined action of these twoforces will thus automaticallykeep the plate at the center line of thewedge.

Further, any tendency of the glass to draw from one pool more than theother will reduce the depth of the glass in that pool DIS llo

Loman aud'ir will naturally be supplier*` the other pool which will bebuilding;r up its level at, its lowermost point.

lt is thus seen thatv the amount of glass to he drawn upwardly, :intltherefore the thirlmes of the sheet. will (lopend upon the amr-uutflowing over the sulimergell edges of the Hunter. provided this; flow iske t within the liiuit at. which the glass in tlie `heet 16 will Supportitself at the speed at which tho rollers 'l5 are driven. Thev wedge 17will cool the intel-iur of the glas-.ii rather than the sul-face, anti,sum rmling, within limite. van he arranged so thut a rapid rate oflrr.\.rin;r can be effected without cooling the surface of the glass tosuch extent :is to (cause deritricaion,

ln the usual methodl of drawing glass it in the temperatur(I of thesui-fare of the glass :ity the drawing point aml in the hou); of theglass which determines the th'irknms of glass, in the sheet at envCertain rate of travel of rollers. I flo not (lopend so greatly upon thetemperature. us the amount, of flaw going into the sheet is determinednot so much lijf the temperature of the glass: drawn upward l' 9..'1 lf)the nniuunt of glass flowing' over the rulmwrgrvtl edges of tlifdrawingring. 'l`herefm'tn the tliirkneflf: of the Sheet will he lirectlj inproportion to the amount of said isuiniersim. other tliing: being equal.

After the glass passes up through the slof in il Coi-m l2 It is still:etw/tri4 1. flou uur. :nm t herr that the Coo "ruim it? are nightfalliulniwlj; (lose luvuwi the glam amil tfzzif'ly Cliii the glu.,` topoint' n lfrrt thm; l tif-telling piatti-willy wzl '.lf'iw not minoffilio Cui'- renti` of uit* :it: u j' point in wht-Ph ity phi tif# mtl herethel willing is lirfih to zitiert its thirlmews,

There is :i tendency for glug; to tli'uw away at its edges when drawn.from an open pool until it finally becomes a round column of glass.This tendcncjv is mfcrrome in 'the presenti invention owing to the fact.that the 'wlles ofthe glas?. teufl to sulhere to the tloater 10. Also,the migo of the; ilzinter ovm' which the glans Hows may time(lepressione lll which serve to feefl uilllitiouul glass to the Gilgenol' the .-shrrt anti lino' inuintrain the Yswlth of the pluto. Holt-r;lil may also he provided in the mule ol' iluL :ung lll. lo muse leediiigoi" mhlilimnil glass :n liu eliges of the Sheei.

l'lmrv, flaws of considerable thirlinf-Ss il; .rimini ant. it is nel tokeep the limiy of in the tank 152 aty low teuuierziture, it muy hr founddesirable to lient the ril l? instead of fooling il, and fooling :niflheating fluidek may he passed therethrough alternato@ ly, or frensiiuultanemxsly, :LQ Conditions muy render desirable., As tu theintroduvmn of cooling wvl fluids siniullaueouly. it

is necessary to introduce a temperuturf-mm trolling medium into the riliin sullluiont volume to fill the passage. heraus@ a l@mail rol ume offluid would rezuh the temperature of the ring before traveling asullirient dif.v tzmrfo within the ril). while a largo rullini@ ofliquid at a given temperature might muso a too ,great lullige iu thetemperature ot' the ril. By ronihining two Streams; of fluiel andffonti'ollinf; their relative proportions, :1 full volume of toolingiluitl, at exactly the teu1- peinture llvsirell. may lio provided.

Referring to Figure 3, l show n ring or limiter 20 which lun` itxlmttoin portion of greater iiuflilmtion than the bottom of the ring lll.The upper portion i9 of they limiter if; prm'ifleil willi n depending);thing@ L that oxtentls heluw the surluce if the glass nnfl serre# :is askimmer, to prevent limiting )ian titles from 0mm-ing the ring. Themolten glans enters the ringr 2f) through openings 2l iu the #illes ofthe ring. A rover 22 larven to `iii-lvl tlm glass in the funk and tohohl the t'luiitor 2l) in plaire, while the sheet is drawn liv n pair ofrollers The loater 2l) is prmillwl with :i rili ifi. ol' wedge-likeform. tin-mmh whirl! tooling tluifl muy he paw-(l l'i'on t'frh owl. m ii'-zitezl by the line 2G of l* lint-lf un ol' tooling mwlium vill l-fpusfwl tlumnji tlw ril for ulistuntiall' mi oiwlizxlt il iill-nfftli nmlro- Vu-vly diret-loll tfiw its maint nl' entry. f'u-iriitlinlf of moreaiuimim tooling' of lio ril: :nul enaliling :im to Yury tlux degree o."rrr-.lling :il turion [indium il tht 'wt-lulu Figure 4. elimini: :inmulmllinwut .Qiuiiizir to hill. exft-iii. that tiir- Cooling' wmlptj isnimh nlV :i Hgiuizitt iiwv "il nur? lio )nullo ol' llillvrrui,nuitrzizil l'iorn that mnflitutiug; the mitin lwly ol" the lloutrr 2li".

Figuur l i' \[|-r1-ruilhi wedge in flri'nil. unl! thi. yizuliwului':llltiuli-ni opt-ning,` 2li um iwf* iwi lull willing miur muy lm lauw-lthrough this upper opt-nlug. turn :i lwiul. :lull rutile-i1 through tiulower opening', rl'lii Hmtvliul |||n \v lu? ol' 'muuiilwlgllllfsul).slum-1' will 'uit umili su' mlm' the gl; -`url; uit-ltr fz Melel, Siulimzitfl'ilh sin lu'- luruliiiutl mi lwpt truigfli uith hws lllli lultythan i'rl`i'zu'lln'-v umtruiulz` whhli muy warp in liiiningf, 'ltere iS:1u :Hlwiulugfv in employing; thtA tooling; uiwliuu: iu thil nmuuul'. inthv grt-:liet mount .wl l-ooling will lw :it the point whore therooliu;r muteriul enterre tlu opening' 2li. Figure ti, and lliew |ioi1itwill he where tlux salgo# of the shout are fli'uou. or rinse thereto.null (lul short will he progressively uriner tfiwui'tl its rntvr. Theteudenty of the sheets to nuiruw in thawing is thus refluretl. Thinfinding of the cooling must he wirt-fully lone und musty not be tooextreuu. as there' will he :i tendency for it. to alfort, the thinkpuwol' the plate, und it is expected that the ill proportions of thesewedges will be so designed as to give only suilicient additional coolingat the edges to maintain the plate against any tendency to otherwisenarrow.

Referring t Fig. 5, which is a plan view, itwill be seen that theopenings 21 are in all four sides of the drawing ring; also that theskimmer 23 extends on all four sides. These openings 2l need not be asnumerous at the ends as on the sides, because only suf ficient glass tomaintain the edges of the. sheet need be fed in ut the ends of the ring.Figure T shows a slight variation in the cooling of the streams :29which form the sheet 30. TheV ring is shown :is provided with two ribs,27, between which a pipe 31 for a cooling or a heating medium is dis-The sheets Q9. as they are drawn upward by the rolls Q8, fuse orcoalesce to form a completed sheet 30.

Figure 8 shows another embodimwt, where the principle of combining theflowing and the drawing is employed, but where in the mid portion of thedrawingr ring is de reused, instead of the pool being partial divided asin some of the other figures. In t is embodiment the glass is keptstraight by the flowin into the pool from o posite sides, in equaamounts, rather than any other factor, as the temperature of the ool.instead of being colder at the interior o the glass, will be thereverse, as in the present system of drawing glass from a ool or bath.

The iloater 45 is shown as iaving submerged openings 46 through whichglass may enter,and a skimmer 47, but it is obvious that a ring orfloater arranged so that the glass will flow over the edge thereof, asshown in Fig. 1, and without the use of a skimmer, can be employed forcollecting a pool.

I claim as my invention:

1. The method of forming sheet glass, which comprises setting up :t flowof molten glass downwardly from opposite directions to opposite sides ofa dividing member, to form a pool, and drawing sheet of glass from saidpool.

2. The method of formi g sheet glass, which comprises flowing strwams ofmolten' glass downwardly from opposite directions into contact with thesides of a 'wedge-like member, ooolin the interior of said member.uniting sai streams and continuing the movement thereof in the form of asheet. 3. The method of forming sheet glass. which comprises flowingstreams of molten glass downwardly from opposite directions into contactwith the sides of a wedgelike member, controlling the temperature ofsaid member, uniting said streams, and continning the movement thereof,in the form of a sheet. y

4. The method of which comprises crea ing two streams o arming sheetglass.

bath, to form a pool,

molten glass by gravity flow, unitin said streams. and continuingmovement t ereof upwardly in the formv of a sheet.

The method of forming sheer. glass, which comprises creating two streamsof molten glass, uniting said stremns cooling the space between thestreams adiacfn; to their line of juncture, and continuing move-- mentthereof in the form of a single sheet.

6. The method of forming sheet giass, which comprises drawing a sheetupwardly hy mils disposed shove a pool of molten glass, maintaining thetemperature surface of the sheet of glass :it a point above said pool,and cooling the surface of the glass at a int between said mils and thefirst name point. l.

7. The method of forming sheet glam, which comprises drawing a sheetfrom a pool of molten glass that is formed by flowing over the edgeolf'a container which is im mersed in a bath of molten glass, andregulating the flow of glass into the container by varying the'depth atwhich the container is positioned in the molten bath.

8. The method of forming sheet glass, which comprises flow' glass from amolten uhawin a sheet from said pool, cooling the glass adjacent to saidpool to such an extent as would determine the thickne of a sheet drawnfrom an o n bath at a iven rate, and restricting the ow of glass romsaid bath to the pool to an amount less than required to form a sheet ofsaid determined thickne.

9. The method of drawing sheet glass, which comprises flowing a streamof molten glass downwardly from a bath of molten.

lass, maintaining an unbroken connection etween the surfaces of the saidbath and stream, and drawing the forward end of the stream of glassupwardly in the form of a sheet.

10. The method of drawing sheet glass which comprises creating twostreams ol molten 'glass moving in directions inclined downwardly withrespect to the horizontal, causing said streams to unite, drawing theunited streams upwardly to form a. sheet` and controlling thetemperature of the united streams ata point beneath their line ofjuncture.

11. The method of forming sheet glass, which com rises directing astream of glass downwardll; and against each face of ,a member ofwedge-like form whose apex is uppermost, causing the sai streams tounite at said apex, and continuing the upward movement of the glass, inthe form of a sheet.

12. The method of forming sheet glass which comprises directing twostreams o. glass downward] from the surface of a pool of molten g ass,continuing the movement of said streams in an upwardlv nf clineddirection, uniting said streams, `and lit llo

lia

continuing the movement thereof upwardly in the form of a sheet.

13. The method 'of forming sheet glass, which comprises submerging adrawing ring ot' dish-like form in a pool of molten glass, to pcrniitflow of molten glass from the edges ot said member to the bottomthereof, and drawin; r a .sheet from a point adjacent to the bottoni ofsaid drawing ring.

14. The method of forming sheet glass, which comprises siibmergiig acontainer having a depressed mid portion in a bath of molten glass, tocause the glass to flow from opposite edges of the container, towardsaid mid portion', under the action of gravity, and drawing a sheet fromsaid mid portion.

15. The method of forming sheet glass, which com rises submerging adrawing ril` having a epressed mid portion in a bat of molten glass, tocause the glass to flow toward said mid portion under the action ofgravity, drawing a sheet from said mid portion, and controlling thetemperature of the glass adjacent to the point of'initial formation ofthe sheet.

16. Apparatus for forming sheet glass, romprising a drawing ring havinga detachable rib of wedge-like form, and means for drawing a sheet ofglass from molten gla at the sides of said rib.

17. Apparatus forl forming sheet glass, comprising a container having adepressed portion toward which glass will flow from the exterior of thecontainer when the container is partially immersed in a bath of moltenlass, means for regulating the depth to which the container is placed inthe bath of glass, and means for drawing a sheet from the .glass whichflows into the rin 18. Apparatus for forming sheet g ass, comprisingr ad'rawin ring of dish form for submerging in a hath of molten glass, sothat the glass will flow toward the midportion thereof, and means fordrawing a sheet from said mid portion.

19. Apparatus for forming sheet glass, comprising a drawing rin 0f dishform for submerging in a bath o molten glass, so that the glass willflow toward the4 mid portion thereof, and means for drawing a sheet fromsaid mid portion, the said ring being provided with`a rib against theopposite sides of which the glass Hows upon enterin the ring.

20. pparatus for formin sheet glass, comprising a' drawing ring aving adepressed mid portion, a rib member extending across the depr portion,means permitting glass to flow downwardly against opposite sides 0f saidrib'when the ring is immersed in a bath of molten glass, and means forcontinuing movement of molten glass from said rib in the form of asheet.

21. Apparatus for forming sheet glass, comprising a drawing ring havinga de pressed mid portion to which molten glass will flow when the ringis partially immersed in the lass, and means for drawin a sheet from tieglass which flows to sai( mid portion, the point of withdrawal bein*normally below the level of the bath o molten glass.

22. Apparatus for forming sheet glass, comprising a drawing rin having adepressed mid portion to w ich glass will flow downwardly in streamsfrom opposite sides of the ring, means for unitin said streams andcontinuing movement t ereof as a single sheet, and means for controllingthe temperature of the streams adjacent to the point of juncturethereof.

23. Apparatus for formin comprising a drawing rin iaving a depressed midportion to wiich glass will flow downwardly in streams from oppositesides of the ring, means for unitin said streams and continuing movementt ereol as a single sheet, and means for controlling the tem erature ofthe streams beneath the point o juncture thereof.

24. Apparatus for forming sheet glass, comprising means for directingtwo streams of glass downwardly from a bath of molten glass and forcausing said streams to unite, and means for continuing movement of theunited streams upward to form a sheet.

25. Apparatus for forming sheet glass, com rising means for directingtwo streams of g ass downwardly from a bath of molten glass and forcausingsaid streams `to unite, means for continuing movement. of thesheet glass,

united streams upwardly to form a sheet,

and means for controllin the tem erature of the glass at a pointadJacent to t e point of juncture of the streams.

26. Apparatus for forming sheet glass comprising a container havin Aa deressed mid portion toward which glass w1 flow from the exterior of thecontainer over the edges thereof when the ring is immersed in a` bath ofmolten glass, and means for drawing a sheet from the glass which co1-lects at said mid portion.

Signed at Butler, Pa., this 17th day of Sept., 1926.

GEORGE E. HOWARD.

